Multiple Cutters on a Degradation Pick

ABSTRACT

A degradation pick for degrading a surface comprises a substantially conical body with a pointed end. A shank is attached to the substantially conical body opposite the pointed end. At least one cutter is disposed within at least one cavity which itself is disposed on an exterior surface of the substantially conical body between the pointed end and the shank.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional Pat. App. No. 61/758,345 which is incorporated herein by reference for all that it contains.

BACKGROUND OF THE INVENTION

The present invention relates generally to the degradation of natural and man-made surfaces as is common in such fields as road milling, mining and construction. More particularly, the present invention relates to increasing the wear resistance of degradation picks commonly used in such processes. In road milling, for example, degradation picks may be secured to the exterior of a rotating drum and brought into engagement with a road surface to remove a layer of the surface in preparation for applying a new layer. In another example, degradation picks may be secured to links of a chain and brought into engagement with the wall of a mine to remove earthen materials. Such uses can wear down a degradation pick quickly.

Degradation picks often comprise a steel body comprising an attachment shank at one end and a super hard tip at an opposing end. As the steel body wears it may fail prior to the super hard tip, prematurely ending the life of the pick. Increasing the wear resistance of degradation picks may extend the life of such picks and thus reduce the frequency that such picks need to be replaced during operation.

Wear to the steel body is especially pronounced on surfaces facing a direction of impact. For example, degradation picks secured to the exterior of a rotating drum may tend to wear on surfaces facing the direction of rotation since these surfaces are most likely to impact a surface. Additionally, it is known to secure degradation picks adjacent an edge of a rotating drum at an angle offset from a line perpendicular to an axis of rotation of the rotatable drum. This offset may position a super hard cutter beyond the edge of the rotating drum to clear aggregate from side walls of a cut which have a tendency to collapse. While this offset may provide a cleaner side wall, it may also expose an exterior of the steel body to impact from a road surface without protection from the super hard cutter.

Consequently, numerous attempts have been made to increase the wear resistance of degradation picks.

One such system is disclosed in U.S. Pat. No. 4,682,987 to Brady et al. which shows heavy duty industrial, mining and general purpose cutting tools comprising hard surface coatings comprising nickel-chromium metal alloy powder and a flux, usually boron and/or silicon. The hard surface is applied in slurry form, dried and then fused in a furnace.

Another such system is disclosed by U.S. Pat. No. 4,725,098 to Beach, which describes a rotary cutting bit for use in mining and excavating applications incorporating an annular groove about a head portion of the bit immediately rearwardly of where a hard tip of the bit is seated and a hardfacing material deposited in the groove in the form of an annular ring.

Another such system is disclosed by U.S. Pat. No. 7,300,115 to Holl et al., which describes a chisel holder for a road milling machine or the like, having a base element supporting a holding neck, a protrusion connected to the base element upstream of the holding neck when viewed in an advancing direction of the tool and a chip breaker formed on the base element and extending, starting at the holding neck, at least partially over the protrusion.

The prior art shows some advancements in increasing the wear resistance of degradation picks; however, it is believed that there is still a need to develop improved wear resistance apparatuses.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the present invention, a degradation pick for degrading a surface comprises a substantially conical body with a pointed end. The pointed end may comprise a super hard cutting element to increase durability. The super hard cutting element may comprise sintered polycrystalline diamond attached to a carbide substrate. The substrate may be attached to a bolster, and the bolster may be attached to the pointed end of the substantially conical body. A shank may be attached to the substantially conical body opposite the pointed end. At least one cavity may be disposed on an exterior surface of the substantially conical body between the pointed end and the shank. At least one cutter, also comprising sintered polycrystalline diamond attached to a carbide substrate, may be disposed within the cavity.

In some embodiments, the carbide substrate portion of the at least one cutter is disposed within the at least one cavity. The polycrystalline diamond portion of the cutter may protrude from the cavity. In other embodiments, the polycrystalline diamond portion is disposed outside of the at least one cavity.

In various embodiments, the polycrystalline diamond portion may comprise a substantially conical geometry, hemispherical geometry or cylindrical geometry. In some embodiments, the at least one cutter comprises a central axis perpendicular to the exterior surface of the conical body. The central axis of the at least one cutter may be offset from a central axis of the substantially conical body by 5 to 85 degrees.

In some embodiments, the degradation pick further comprises a plurality of cutters. A combination of the plurality of cutters may form between 1 and 40% of a circumference of the substantially conical body. The plurality of cutters may be equally spaced from the pointed end of the substantially conical body.

In some embodiments, a block with a hole therein may be disposed on a surface of a rotatable drum. The shank of the substantially conical body may be disposed within the hole. The hole may sit at an angle offset from a line perpendicular to an axis of rotation of the rotatable drum and the block may be disposed substantially adjacent an edge of the rotatable drum. The angle of the hole may cause the pointed end of the substantially conical body to overhang the edge of the rotatable drum. The angle of the hole may also cause the at least one cutter to be disposed substantially on a line perpendicular to the axis of rotation of the rotatable drum and passing through the edge of the rotatable drum. The at least one cutter may be disposed along a line perpendicular to an axis of rotation of the rotatable drum and in a direction of rotation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a magnified orthogonal view of an embodiment of a degradation pick of the present invention secured to an exterior of a rotatable drum.

FIG. 2 is a perspective view of an embodiment of a degradation pick of the present invention.

FIGS. 3 a and 3 b are longitudinal section views of other embodiments of degradation picks comprising at least one cutter disposed within at least one cavity.

FIGS. 4 a, 4 b and 4 c are perspective views of embodiments of degradation picks comprising various cutter geometries.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures, FIG. 1 discloses a front orthogonal view of a rotatable drum 100 such as may be used in road milling, mining or construction. A plurality of blocks 110, each comprising a hole 115 therein, may be disposed around an exterior surface of the rotatable drum 100. A plurality of degradation picks 120, each comprising a substantially conical body 125 comprising a pointed end 130 opposite a shank (hidden), may be secured to the plurality of blocks 110 by disposing each shank within a hole 115. The rotatable drum 100 may be rotated to bring a super hard tip 135 disposed on the pointed end 130 into contact with and degrade a surface.

While the plurality of blocks 110 are generally positioned such that the pointed end 130 may face in a direction of rotation, it is known to position blocks substantially adjacent an edge of a rotatable drum at an angle offset from a line perpendicular to an axis of rotation of the rotatable drum. This configuration, which is shown in the magnified view of FIG. 1, may position the hole such that the pointed end 130 overhangs the edge of the rotatable drum 100. By allowing the pointed end 130 to overhang the edge of the rotatable drum 100, the super hard tip 135 may act to clear aggregate from side walls of a cut which have a tendency to collapse. However, while this offset may provide a cleaner side wall, it may also expose an exterior of the substantially conical body 125 to impact from a road surface without protection from the super hard tip 135.

The substantially conical body 125 may be made of steel and consequently wear at a faster rate than the super hard tip 135. This may prematurely limit the useful life of a degradation pick because significant wear may not have occurred at the super hard tip 135 when the steel is in need of replacement. To offset extensive wear to the substantially conical body 125 and thus extend the useful life of a degradation pick, at least one cutter 160 may be disposed within a cavity on an exterior surface of the substantially conical body 125.

Embodiments of the present invention may position the at least one cutter 160 substantially on a line perpendicular to an axis of rotation of the rotatable drum 100, passing through the edge of the rotatable drum 100 and/or in a direction of rotation.

FIG. 2 discloses an embodiment of a degradation pick 200 of the present invention for degrading surfaces. The degradation pick 200 shown comprises a substantially conical body 205 with a pointed end 210. The pointed end 210 may comprise a super hard cutting element 215 to increase the durability of the pointed end 210 of the substantially conical body 205. The super hard cutting element 215 may comprise sintered polycrystalline diamond 220 attached to a carbide substrate 225. The carbide substrate 225 may be attached to a bolster 230, and the bolster 230 may be attached to the pointed end 210 of the substantially conical body 205.

The degradation pick 200 further comprises a shank 240 attached to the substantially conical body 205 opposite the pointed end 210. In the embodiment shown, the shank 240 comprises a substantially circular cross-section. However, in other various embodiments, the shank may also comprise a substantially polygonal cross-section or asymmetrical cross-section.

FIG. 3 a discloses another embodiment of a degradation pick 300 a comprising at least one cavity 350 a disposed on an exterior surface 355 a of a substantially conical body 305 a between a pointed end 310 a and a shank 340 a. At least one cutter 360 a is disposed within the at least one cavity 350 a. As shown in the figure, a central axis of the at least one cutter 360 a may be perpendicular to the exterior surface 355 a of the substantially conical body 305 a. As is also shown in the figure, the central axis of the at least one cutter 360 a may also be offset from a central axis of the substantially conical body 305 a by 5 to 85 degrees. In this formation, the at least one cutter 360 a may shield the substantially conical body 305 a from wear during a surface degradation operation. The at least one cutter 360 a may be removable and replaceable to prolong the life of the degradation pick.

The at least one cutter 360 a may comprise polycrystalline diamond 362 a attached to a carbide substrate 367 a. The carbide substrate 367 a may be disposed within the at least one cavity 350 a. In various embodiments, the carbide substrate 367 a may be brazed or press-fit within the at least one cavity 350 a.

In the embodiment shown, the polycrystalline diamond 362 a is protruding from the at least one cavity 350 a such that the carbide substrate 367 a is completely disposed inside the at least one cavity 350 a.

FIG. 3 b discloses yet another embodiment of a degradation pick 300 b comprising at least one cutter 360 b disposed within at least one cavity 350 b. In the embodiment shown, polycrystalline diamond 362 b forming part of the at least one cutter 360 b is completely disposed outside of at least one cavity 350 b.

FIGS. 4 a, 4 b and 4 c disclose various embodiments of degradation picks 400 a, 400 b and 400 c each comprising a plurality of cutters 460 a, 460 b and 460 c disposed within cavities thereon. While FIGS. 4 a, 4 b and 4 c show each degradation pick comprising two cutters equally spaced from the pointed end of a substantially conical body, it is anticipated that any number of cutters may be used. In embodiments where a plurality of cutters is employed, a combination of the plurality of cutters may make up between 1 and 40% of a circumference of the substantially conical body. Each of the plurality of cutters 460 a, 460 b and 460 c may comprise polycrystalline diamond protruding from the cavities.

As shown, the polycrystalline diamond may comprise a substantially hemispherical geometry (as shown in FIG. 4 a), a substantially cylindrical geometry (as shown in FIG. 4 b), or a substantially conical geometry (as shown in FIG. 4 c). Also, in the embodiments shown, the shank comprises a central axis offset from a central axis of a substantially conical body.

Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention. 

What is claimed is:
 1. A degradation pick, comprising: a substantially conical body comprising a pointed end; a shank attached to the substantially conical body opposite the pointed end; at least one cavity disposed on an exterior surface of the substantially conical body between the pointed end and the shank; and at least one cutter disposed within the cavity.
 2. The degradation pick of claim 1, wherein the at least one cutter comprises polycrystalline diamond attached to a carbide substrate.
 3. The degradation pick of claim 2, wherein the polycrystalline diamond comprises a substantially conical geometry.
 4. The degradation pick of claim 2, wherein the polycrystalline diamond comprises a substantially hemispherical geometry.
 5. The degradation pick of claim 2, wherein the polycrystalline diamond comprises a substantially cylindrical geometry.
 6. The degradation pick of claim 2, wherein the carbide substrate is disposed within the at least one cavity.
 7. The degradation pick of claim 2, wherein the polycrystalline diamond is disposed outside of the at least one cavity.
 8. The degradation pick of claim 2, wherein the polycrystalline diamond of the cutter protrudes from the cavity.
 9. The degradation pick of claim 1, wherein the at least one cutter comprises a central axis perpendicular to the exterior surface of the substantially conical body.
 10. The degradation pick of claim 1, wherein the at least one cutter comprises a central axis offset from a central axis of the substantially conical body by 5 to 85 degrees.
 11. The degradation pick of claim 1, further comprising a plurality of cutters disposed on the exterior surface of the substantially conical body between the pointed end and the shank.
 12. The degradation pick of claim 11, wherein a combination of the plurality of cutters forms between 1 and 40% of a circumference of the substantially conical body.
 13. The degradation pick of claim 11, wherein the plurality of cutters are equally spaced from the pointed end of the substantially conical body.
 14. The degradation pick of claim 1, further comprising a block with a hole therein disposed on a surface of a rotatable drum, wherein the shank of the substantially conical body is disposed within the hole.
 15. The degradation pick of claim 14, wherein the block is disposed substantially adjacent an edge of the rotatable drum and the hole sits at an angle offset from a line perpendicular to an axis of rotation of the rotatable drum.
 16. The degradation pick of claim 15, wherein the angle of the hole causes the pointed end of the substantially conical body to overhang the edge of the rotatable drum.
 17. The degradation pick of claim 16, wherein the angle of the hole causes the at least one cutter to be disposed substantially on a line perpendicular to the axis of rotation of the rotatable drum and passing through the edge of the rotatable drum.
 18. The degradation drum of claim 14, wherein the at least one cutter is disposed along a line perpendicular to an axis of rotation of the rotatable drum and in a direction of rotation.
 19. The degradation drum of claim 1, further comprising a cutting element disposed on the pointed end of the substantially conical body.
 20. The degradation pick of claim 1, wherein the shank comprises a central axis offset from a central axis of the substantially conical body. 